Endometrial ablation (i.e., the removal or destruction of the endometrial lining of the uterus) is used as an alternative to hysterectomy for treating menorrhagia, or other uterine diseases. One prior technique for performing endometrial ablation employs a resectoscope (i.e., a hysteroscope with a built-in wire loop or other ablative devices) that is inserted transcervically into the uterus, and uses radio-frequency electrical current (RF current) to remove or coagulate the endometrial tissue. These standard techniques typically are performed in a hospital setting and importantly utilize hysteroscopy for visualization of the procedure while treating the uterine lining.
Some approaches make use of heated fluid to ablate the endometrium. For example, early journal articles describe the use of steam to treat uterine hemorrhage. The use of steam for this purpose was later discredited, apparently due to patient morbidity and mortality. See, e.g., Fuller U.S. Pat. No. 6,139,571. More recent descriptions of the use of injecting hot fluid into the uterus have been described. Uterine therapies employing a contained fluid have also been described.
In an effort to simplify the procedure, approaches have been developed that do not require concurrent hysteroscopic visualization. In practice, many of these techniques recommend that the physician or user employ hysteroscopy to visualize and inspect the uterine cavity prior to performing the endometrial ablation procedure. In addition, hysteroscopy may be employed at the conclusion of the endometrial ablation procedure as a method to inspect the uterine cavity post treatment. During this hysteroscopic inspection, the physician is verifying that the uterine cavity is not perforated although perforations may not be readily apparent even with hysteroscopic visualization. In general, a physician seeks to avoid perforations for many reasons including the potential for unintended injuries to neighboring organs and maintaining or confining the treatment area to specifically the uterine cavity in the case of endometrial ablation procedures.
Endometrial ablation techniques that do not require active hysteroscopic visualization during treatment operation are commonly referred to as “blind” techniques since the physician is using tactile feel, or markers and indicia on the endometrial ablation device to indicate proper placement of the device in the uterine cavity. One of these particular devices utilizes a balloon-based system using heated saline as the thermal energy source for the ablation of tissue. High frequency, or radiofrequency (RF), energy has also been used to perform thermal ablation of endometrial tissue. Current products for performing endometrial ablation include the NOVASURE® procedure and a system marketed under the trade name THERMACHOICE®, by Ethicon, Inc. of Somerville, N.J. Cryogenic ablation, or “cryoablation,” such as HER OPTION® from American Medical Systems, Inc., is another endometrial treatment approach. All of the products above are characterized as “blind” or not requiring direct hysteroscopic visualization during the treatment.
In utilizing an endometrial ablation technology that does not require hysteroscopic visualization, it would be beneficial to employ a test to verify that the uterine cavity is intact or unperforated prior to performing the treatment. Such tests are referred to as uterine integrity tests and these tests can be performed with endometrial ablation procedures and any procedure of the uterus or hollow body cavity or organ. In addition, these tests can be used with hysteroscopic procedures since a perforation may not be readily detected even under direct vision.
Integrity tests employ saline or gas, preferably carbon dioxide gas, as agents to verify if the uterine cavity is intact in regards to holding fluid or gas pressure. The gas or fluid is supplied under pressure to the uterine cavity and a leak in the uterine cavity, whether it is a perforation, an unsealed cervical canal, or the effect of excess fluid exiting the fallopian tubes, can be discerned. Stern et al. (U.S. Pat. No. 5,562,720) and Sampson et al. (U.S. Pat. No. 6,554,780, U.S. Pat. No. 6,743,184, U.S. Pat. No. 6,872,183, and U.S. Pat. No. 7,063,670) describe such pressure techniques while other approaches check for fluid imbalances between an input source and output collection using volume measurements. Other approaches mention using flow rate and pressure measurements.
For monitoring the therapeutic energy application during the procedure, some technologies monitor the internal pressure of heated saline within a balloon that is placed within the uterus, or the impedance of radio frequency energy within the wall of the uterus. These technologies have automatic termination steps if the pressure, impedance, or volume levels reach certain thresholds. At the initiation of the procedures for all of the above mentioned systems, the inaccurate placement and management of the therapeutic device by the physician within the uterine cavity can reduce the ability to perform a safe and consistent ablation procedure. For these technologies, the ability of the device to perform a complete endometrial ablation procedure depends upon the tactile movements and placement of the device by the physician in terms of depth of placement or achieving complete contact with the interior lining with the delivery device mechanism. As an example, a radio frequency device deploys an RF array within the uterine cavity. The depth of insertion can vary by patient and physician. By not contacting the endometrium in more distal or proximal locations, the efficacy of the procedure could alter or be affected. For thermal balloon procedures, a similar effect can occur due to the depth of device placement. For both of the technologies, the system cannot provide information or assessment for the proper and consistent placement of the device in the uterine cavity. Alternatively, an amorphous ablation technology such as the free flow of heated saline does not have this physical limitation however even this technology, known as Hydro Thermo Ablation or HTA, relies heavily on the placement of the device by the physician to prevent leaking out of the endocervical canal.
Systems that depend heavily on physician manipulation or intervention during the procedure have been characterized as being “technique sensitive”. The requirement for a physician to properly manipulate a delivery device and react appropriately before and during an endometrial ablation procedure can lead to an increase of adverse events or unreliable patient outcomes. This is particularly evident when threshold values prior to and during a procedure fall within a range requiring physician intervention or adjustment.
The following describe a control system that overcomes these deficiencies for a technology that provides vapor energy in combination with a number of unique and sequenced steps designed to ensure patient safety and procedural consistency. The control system also assesses delivery device placement and sealing within the uterine cavity and endocervical canal by providing information for the physician when additional pressure within a sealing balloon at the cervix may be needed.